Sensibilidade e especificidade do "California Mastitis Test" como recurso diagnóstico da mastite subclínica em relação à contagem de células somáticas

Abstract

The California Mastitis Test (CMT) is a simple and widely used diagnostic tool for subclinical mastitis. It is used even in areas where laboratory facilities are available for diagnosis and monitoring program purposes. CMT usually score 1-5, where 1 indicates a completely negative reaction and 2-5 increasing degrees of inflammatory reaction of the udder. The reactions 2-5, 3-5 or 4-5 may be considered as indicative of subclinical mastitis, because they are related to an increase of the somatic cell count (SCC) in the milk. This variation, however, may produce either false-positive or false-negative results. The aim of this study was to assess the sensitivity and specificity of the CMT in comparison with SCC. A total of 3,012 quarter milk samples from 760 lactating cows were examined. CMT was evaluated at the moment of sampling at cow side and SCC in the laboratory, with a fluoro-opto-electronic method (Fossomatic 90). The average CCS (x 1,000 cells/ml) for CMT scores were: 1 (79.9), 2 (333.5), 3 (670.3), 4 (1,354.0) and 5 (4,455.6). Three options for CMT interpretation were evaluated in relation to a range of CCS, starting from 100,000 cells/ml: (a) 1 versus 2, 3, 4, and 5; (b) 1 and 2 versus 3, 4 and 5; and (c) 1, 2 and 3 versus 4 and 5. The sensitivities of CMT scoring to detect quarters with SCC >200,000/ml were 79%, 61% e 34% for options a, b and c, respectively. The sensitivities of CMT scores for SCC >500,000/ml for options a, b and c, were, respectively, 93%, 82% e 54%. The sensitivity of CMT scores to identify subclinical mastitis was satisfactory (above 80%) when options b and c were used. The interpretation of CMT score 3 as negative for subclinical mastitis was considered as adequate (sensitivity around 80%) only when CCS ranged between 1,200,000 and 1,400,000 cells/ml. The specificities of CMT scoring for CCS of 200,000 and 500,000 were, respectively, 90% and 80% (option a), 97% and 90% (option b) and 99% and 97% (option c).

Teores de proteína, gordura e sólidos totais no leite de vacas da raça Jersey criadas no Estado de São Paulo durante o primeiro mês de lactação

“…Na literatura compulsada, encontraram-se citações referentes ao sistema de manejo alimentar, determinando significativa influência nos teores de gordura do leite. 17 Segundo Brito et al 18 , as variações dos teores lácteos de gordura seriam decorrentes, principalmente, das variações da quantidade de gordura sintetizada nos ácinos da glândula mamária a partir dos ácidos graxos de cadeia curta (acetato e butirato), produzidos durante a fermentação ruminal de forragens e outros alimentos ricos em fibras. Pelas características do manejo alimentar dos rebanhos de bovinos produtores de leite utilizados nesta pesquisa foi assegurado que na alimentação dos animais utilizados havia a quantidade de fibras necessárias para a produção da gordura no leite.…”

Prevalence and etiology of buffalo mastitis and milk somatic cell count in dry and rainy seasons in a buffalo herd from Analândia, São Paulo State, Brazil

“…During physical examination and strip cup test no changes were observed in mammary glands or in milk characteristics, respectively. Brito et al (1997), positive reaction in CMT generally indicates inflammatory reaction in the mammary gland, suggesting subclinical mastitis. However, other factors of non-infectious origin, such as lactation stage, animal age and season, among others, may also influence CMT results, which is considered an indirect indicator of milk SCC, but the effects are minimal in uninfected mammary glands (Reneau, 1986;Harmon, 1994).…”

Efeito da massagem do úbere ao final da ordenha no leite residual e na ocorrência de mastite em vacas leiteiras

“…O CMT foi escolhido por fornecer resultados imediatos, ser de baixo custo e ter correlação positiva com a inflamação. Brito et al (1997) e Barbosa et al (2002) encontraram sensibilidade de 82% do CMT em relação à contagem de células somáticas, considerando-se como reações positivas a ocorrência de mastite subclínica. Neste experimento um dos ordenhadores, cego para os tratamentos aos quais as vacas foram alocadas, foi treinado para a leitura dos testes.…”